The present invention relates to a gas content measuring apparatus, according to the preamble of claim 1.
The invention also relates to a measuring method.
Measuring apparatuses of this kind are used, for example, to measure oxygen content.
According to the prior art, measuring arrangements have been implemented, in which a coherent element is used as the light source and the path of the light is arranged, with the aid of a mirror, to travel twice through the measuring chamber. Using this arrangement brings all of the measurement electronics to the same side of the measurement channel. In solutions according to the prior art, achieving adequate measurement accuracy requires the creation of a relatively long measurement channel.
One source of measurement error is the errors caused by reflections of the coherent light signal. The reflections form diffused light, leading to variations in intensity that—particularly in the form of the interference phenomenon—disturb measurement. Reflections back to the light source are also a source of measurement error.